Trick that often works for me: create a ticket in JIRA, explain well what has to be done, how, document gotchas etc.; assign to yourself; if it's a code ticket, create a local branch with ticket number.
I usually procrastinate when it's not clear what exactly has to be done and how, and writing it down somewhere helps immensely.
The mental game is very important. Definitely hard to work on the things that actually matter - they are usually difficult, new, more intricate to setup, etc. What I've found to work is to "just start on it" - starting is the hardest part. Telling yourself you'll do 15 minutes of it or something, so you will actually start. Usually, when the 15 minutes are up, I won't be stopping. The inertia goes from "not going it" to "doing it" and it's hard to change ha